1. Field of the Invention
This invention pertains to new methods and processes which can be used in the cleaning of articles, especially those soiled with pigment soil, and in particular, the washing or cleaning of all types of articles in aqueous-surfactant baths. Textile laundering is probably the most important application area of such cleaning methods.
2. Statement of Related Art
The laundering process of textiles using conventional laundering agents is known to involve the breaking up and loosening of the soil on or from the fiber. Considerable fractions of the soil represent components which are insoluble in the wash bath, and which pass over into the wash bath in the form of small undissolved particles. Adequate suspension of the loosened soil particles is then a prerequisite for effective laundering, in order to prevent their redeposition and simultaneous graying of the washed material. Conventional detergents contain additives which especially serve this purpose. However, adequate soil suspending ability is also regarded as an important function of the builder constituents of conventional laundry detergent formulations, which are known to contain synthetic surfactant components in admixture with such builder components.
It is also known that in modern laundry detergents with a reduced content of phosphate builders, the synthetic crystalline zeolites used as phosphate substitutes, and especially the corresponding very finely-divided insoluble zeolite NaA of detergent grade counteract redeposition and combat graying because of the large solid surface area which they make available.
The laundry detergent literature contains numerous suggestions for reducing the graying tendency and thus improving the secondary washing power. All these suggestions are aimed almost exclusively at improved suspension, solubilization and stabilization of the particulate soil in the wash bath, even and precisely in the rinse-out cycles of the washing process, in which the tendency for redeposition of dissolved particulate soil is increased by dilution of the laundry chemicals. A fundamentally different approach is described in U.S. Pat. No. 3,694,364. It is therein suggested that a so-called "dirt trap" material should be used to take up and undissolved particulate soil from the wash bath, possibly together with the prevention of anionic coloring material transfer. This dirt trap material consists of a water-insoluble cellulose cloth with a modified surface. This surface is provided with secondary and/or tertiary polyamine compounds which are to be retained on this surface in that the cellulose surface is initially given an anionic character. This is accomplished by the introduction of acid groups, for example via phosphorylation, carboxymethylation and the like. For subsequent coating with polymeric amines, polyethylene amines are considered especially suitable which have a degree of polymerization of 2-50,000, especially 20-20,000 monomer units per molecule, and in which about 10-50% of the amino groups are occupied with stearic acid residues. Cloths provided with such a finish are introduced into the laundry process together with conventional textile detergents. In this way soil is to be deposited from the wash bath onto the cloth surface. These soil components can be separated from the washed material after laundering and thrown away with the dirt trap cloth. To be sure, the document taken under consideration describes the production and nature of the surface-finished, flat cellulose substrate structure. However, no detailed information is given on the laundering results achievable with it.
The concept of reducing anionic dye transfer in textile laundering, caused by bleeding of anionic dyes not adequately fixed on the fiber, by simultaneously using polycationic auxiliaries which bind anionic dye fractions dissolved in the wash bath also appears in the relevant literature in another connection. Thus, European Pat. No. 0,044,003 describes a liquid detergent which consists of selected nonionic surfactants in admixture with textile-softening quaternary ammonium salts, to which an ammonium group-containing cationic starch ether has been added. In laundry experiments without soil loading and under process conditions which were not more closely specified, increased reflectance values were obtained on white cotton cheesecloth washed along with it, when material pieces dyed with colors that bleed are washed with the new laundry detergent. The loading of the wash bath with undissolved particulate soil and the problems deriving from this are not discussed. The same is true from the teaching of European Pat. No. 0,033,815, wherein, in order to prevent dye transfer to the bath, an agent is added which contains a cellulose carrier material with an application of especially glycidyltrimethylammonium chloride or the corresponding halogenated compound. These superficial detergent auxiliaries are intended to control the undesirable transfer of any dyes present in a liquid wash bath. It is mentioned that reuse of these auxiliaries for the indicated purpose is possible. The pigment soil problem from ordinary textile laundering in surfactant wash baths or in other cleaning processes is not mentioned.